The shift in the concept of state sovereignty over airspace amidst the dynamic evolution of international defense cooperation, specifically focusing on the implementation of overflight clearance. Employing a normative legal research method with a literature study approach, this paper examines the alignment between the principle of complete and exclusive sovereignty under Article 1 of the 1944 Chicago Convention and the operational efficiency needs of joint military activities. The findings indicate that the bureaucratic rigidity of traditional ad hoc diplomatic overflight clearances often creates strategic bottlenecks in modern defense diplomacy. Consequently, a paradigm shift has emerged, transitioning from a defensive-exclusive sovereignty toward a more adaptive framework. Pre-conditioning airspace access through institutionalized agreements, such as Status of Forces Agreements or Defense Cooperation Agreements (DCA) (Shaw, 2017), does not diminish state sovereignty. Instead, it serves as a legitimate manifestation of state sovereignty based on consent, successfully balancing national security with global defense interoperability. These findings carry significant implications for the development of national air law policies in response to contemporary geopolitical security landscapes. States are required to formulate precise domestic regulatory frameworks to accommodate military alliance needs without undermining national oversight and territorial integrity. Thus, this approach ensures that defense cooperation operates effectively, structurally, and accountably.